1.) behind my apartment on an walking path, taking my dog for a night walk! 2.)we were on our way home and i always look up in the sky to observe the stars, when, in the corner of my eye, i saw a big flashing light. 3.) my first thought was, it was an airplane, after a closer look i thought it was an satellite. 4.) like stated before, i came to the conclusion it must have been an satellite, but then it did things, no airplane and no satellite are doing. now, i am familiar with airplanes and i also witnessed countless satellites, but this object did weird things. 5.) first i began to notice that it can't be an satellite, it was way to slow, i mean, really slow. then there was one pulsating light that came up randomly, not like on airplanes. after the pulsating light turned dark it took 10-15 seconds and one bright flash appeared and this also not regularly.. i was observing this object for around 30 minutes, when i first saw it, it came from the north , heading north east but a plane or an satellite would have taken 1-2 minutes to be out of sight, not this thing. it was far up in the sky and the sky was/is clear.. no clouds.. the object was hardly to see and i could only spot it when the pulsating light came on or after a flash, it also moved in circles, meaning no straight path. it is so hard to explain what it did. 6.) my actions during the sighting ? i sat down on the ground, my dog next to me and i just looked up to the sky to see what this is all about, i have never witnessed anything like this before, my heart was pounding. trying to explain it and you simply can't. conventional aircraft? i don't think so, satellite? definitely not. we have airplanes / helicopters over this area every day, i know the flight path and like i said before, in nighttime i often look up to the sky and follow satellites.. i am 100% convinced that it was none of those and i hope somebody else in north california witnessed the same thing. 7.) it stopped... that's how i lost sight.. there was no pulsating / flashing anymore.. after observing it for around 30 minutes it suddenly stopped. i changed my position to get a larger view of the night sky and i knew where the object must have been, but nothing happened anymore.. i waited another 5 minutes and decided to go home and fill out this report.